The present invention relates to the field of meat processing, and more particularly to apparatus and methods for deboning a piece of meat having an elongate bone portion such as a hog carcass middle or loin.
In slaughterhouses, after eviscerating, beheading and chilling, animal carcasses are, as a first primal cutting step, separated through the backbone in two carcass halves, each being then further processed to obtain other primal cuts. In pork slaughtering, such further primal cuts include hind and front foot, ham, shoulder and a remaining portion commonly referred to as the xe2x80x9cmiddlexe2x80x9d which includes loin and belly portions with ribs attached thereto, each of these meat portions being provided with a layer of back fat. To further subdivide the middle, a manual method commonly used in slaughterhouses consists of cutting the ribs at a predetermined loin/flank separation area along a direction generally parallel to the backbone with a cutting tool commonly referred to as a xe2x80x9cscribe sawxe2x80x9d, and then manually removing the loin portion from the middle while leaving most of the back fat behind by pulling a hand tool provided with an elongate blade or thread secured at both ends thereof to a pair of handles, which blade or thread extends through the opening or kerf provided by the scribe saw. Alternatively, automated apparatus commonly known as xe2x80x9cmiddle splittersxe2x80x9d can be used for separating the loin and belly portions of the middles, such as those disclosed in U.S. Pat. No. 3,159,869 issued on Dec. 8, 1964 to Vogt et al., in U.S. Pat. No. 4,662,029 issued on May 5, 1987 to Helsene et al., in U.S. Pat. No. 5,407,384 issued on Apr. 18, 1995 to Boody et al. and in U.S. Pat. No. 5,882,252 issued on Mar. 16, 1999 to Boody et al. Apparatus commonly known as xe2x80x9cloin pullersxe2x80x9d are also used to separate back fat from loins that have previously been separated from the bellies. Such loin pullers are disclosed in U.S. Pat. No. 4,189,806 issued on Feb. 26, 1980 to Heyningen and in U.S. Pat. No. 4,979,269 issued on Dec. 25, 1990 to Norrie.
Once the back fat has been removed from the loin, the latter can be further processed to produce various secondary cuts, including boneless cuts such as back boneless long and short cuts, boneless sirloin, tenderloin and boneless chops. Typically, a first deboning step consists of removing the main part of the spine from the loin, leaving only back ribs and feather bones on the partially deboned loin, which remaining ribs and bones can be removed in a further step to provide fully deboned meat. Usually, that first loin deboning operation is manually performed by an operator using a powered rotary or band saw for making a longitudinally cut along the half spine on both sides thereof through the back ribs and the feather bones portions, to allow removal the spine from the loin. While such cutting operation can be performed in a single transverse straight cut through both back ribs and feather bones simultaneously, it is preferably done in two angular cuts sequentially performed through the backs ribs and the feather bones, to reduce the amount of lean meat remaining on the removed spine. Such manual cutting techniques suffer from important drawbacks. Manual deboning is hazardous and time-consuming for the butchers, and provides relatively poor control over the amount of lean meat remaining on the removed spine, which must be kept at a minimum, as well as over the back ribs length remaining on the loin, which must be maximized, to optimize economic value and quality of the cuts.
As an alternative to manual deboning, automated deboning apparatus for removing the spine from a loin or half carcass middle have been known for years. Such an apparatus is disclosed in U.S. Pat. No. 3,982,299 issued on Sep. 28, 1976 to Kompan, which apparatus comprises a knife for feeding a loin to a cutting station using a band saw to make a transverse straight cut through the spine at a predetermined distance from the spine ridge. As for the first manual technique discussed above, the use of such a single straight cut apparatus is not advantageous since it generates significant lean meat loss. Another apparatus using the double-cut approach is disclosed in U.S. Pat. No. 4,134,181 issued on Jan. 16, 1979 to Schneider, which apparatus comprises a conveyor having a concave surface adapted to receive a corresponding outer convex surface of a loin for sequentially feeding thereof to a first rotary saw for making a longitudinal cut in a first, horizontal plane along the spine through the feather bones as spine extensions, to a second rotary saw having its blade being angularly oriented with respect to the blade of the first rotary saw to make a second longitudinal cut in a corresponding second plane along the spine, and to a third rotary saw for making a longitudinal cut in a third, vertical plane along the spine for separating the feather bones from the loin eye. Although representing an improvement over the above prior art apparatus, as for the second manual technique discussed above, the use of such a double-cut apparatus is also disadvantageous in that it still produces removed spines showing a significant otherwise valuable lean meat amount leaved thereon, which is therefore lost.
In an attempt to optimize the cut, another cutting approach is used by a deboning apparatus disclosed in U.S. Pat. No. 5,746,648 issued on May 5,1998 to Wilhelmus et al., which apparatus provides spine removal from a half carcass middle transported on a conveyor, using a cylindrical separating element having a circular toothed cutting edge which rotates at high speed for performing a cut about and along the spine in a plane perpendicular to the conveying direction, while the separated spine portion is discharged through the opening which extends throughout the cylindrical separating element. The circular shape of the cutting edge allows a cut showing an arcuate profile that better conforms to the general section of the spine, and therefore minimizes the lean meat left thereon. However, the friction of the cutting edge on the meat piece due to the high rotation speed of the separating element may induce local heating of the meat piece, which may affect its quality. Moreover, high rate repetitive cuts of the teeth through the meat piece may cause undesirable meat slashing that can also affect meat quality. Furthermore, since the separating element is provided with teeth showing a conventional ramp shape, the apparatus as taught by Wilhelmus generates bone dust or chips remaining behind in the meat piece, which may further adversely affect its quality. A solution to the latter problem is disclosed in European Patent Application published on Feb. 3, 1999 to Meerdink under No. 894 438, which consists of providing the cylindrical separating element with a cutting edge showing a series of teeth each of which is embodied with a guide surface directed toward the inner side element, such that bone dust or chips are carried away to the inside and contamination of the meat piece is therefore prevented. However, even if the apparatus of Meerdink may prove to avoid contamination of the meat piece by bone dust or chips as opposed to the apparatus of Wilhelmus, neither of those proposes a solution to the meat heating and slashing problems.
It is therefore an object of the present invention to provide apparatus an method for deboning a piece of meat having an elongate bone portion, which provide control over the meat left on the removed bone, while preserving the quality of the deboned meat piece.
According to the above object, from a broad aspect of the present invention, there is provided an apparatus for deboning a piece of meat having an elongate bone portion, comprising holding means for maintaining the piece of meat in a predetermined cutting position wherein its elongate bone portion is substantially aligned with a longitudinal axis defined by said holding means, and a cutting tool including an elongate shearing knife having a base portion pivotally mounted on a support structure and an inwardly arcuate section defining a longitudinally extending cutting edge. The cutting tool further includes means mounted on the structure for selectively controlling pivotal movement of the knife between a first position allowing the piece of meat to be disposed in the predetermined cutting position and a second position wherein the elongate bone portion is separated from the deboned meat piece following travel of the cutting edge through the meat piece according to a curvilinear cutting path transversely extending about the longitudinal axis.
According to another broad aspect of the invention, there is provided an apparatus for deboning a piece of meat having an elongate bone portion, said apparatus comprising holding means for maintaining the piece of meat in a predetermined cutting position wherein its elongate bone portion is substantially aligned with a longitudinal axis defined by said holding means, and a cutting tool including a pair of elongate shearing knives having respective base portions pivotally mounted on a support structure and having respective inwardly arcuate sections defining longitudinally extending opposed cutting edges. The cutting tool further includes means mounted on the structure for selectively controlling pivotal movement of the knives between a tool open position wherein the knives are in a spaced relationship allowing the piece of meat to be disposed in the predetermined cutting position and a tool closed position wherein the opposed cutting edges of the knives are brought into contact to separate the elongate bone portion from the deboned meat piece following respective travels of the cutting edges through the meat piece according to convergent curvilinear cutting paths transversely extending about the longitudinal axis.
According to a further broad aspect of the invention, there is provided a method of deboning a piece of meat having an elongate bone portion, comprising the steps of: maintaining the piece of meat in a predetermined cutting position wherein its elongate bone portion is substantially aligned with a longitudinal axis; and shearing the piece of meat according to a curvilinear cutting path transversely extending about the longitudinal axis to separate the elongate bone portion from the deboned meat piece.
According to a still further broad aspect of the invention, there is provided a method of deboning a piece of meat having an elongate bone portion, comprising the steps of: maintaining the piece of meat in a predetermined cutting position wherein its elongate bone portion is substantially aligned with a longitudinal axis; and shearing the piece of meat according to two convergent curvilinear cutting paths transversely extending about the longitudinal axis to separate the elongate bone portion from the deboned meat piece.